If you haven't already seen it, check out the Pew Forum's new Survey on the U.S. Religious Landscape here.
You can compare various demographic aspects of different religious groups in the U.S., such as geographical distribution, economic status, gender distribution, racial distribution, and so forth.
I have yet to read the whole report, but I found the following information particularly interesting:
One aspect of note is that, not really surprisingly, evangelical Christians constitute the largest religious group (or group of groups) in the U.S. at 26.3% (and of those, the largest groups are the Baptists at 10.8% of the entire U.S. population). What I had not realized is that the second largest group is Catholics 23.9%. And so, taken together, evangelicals and Catholics constitute roughly half of the U.S. population. Evangelicals have a higher percentage in the southern states, while Catholics seem to be relatively evenly spread out.
Evidently, Hindus have the highest marital percentage at 79% and the lowest number of current non-married divorced rate at only 5%.
For all of this information and more, be sure to check out the survey. I also hear that there is some interesting information about changing religious affiliations in the full report (which I have not read yet), such as rates of people joining and/or leaving particular religious groups (evidently around 1/3 of people who were raised Catholic no longer consider themselves Catholic and so forth).